A computer‐controlled system for measuring bulk resistivity of insulating solids as a function of temperature is described. The measuring circuit is a modification of that given in the ASTM standard D257‐66, to allow for a number of operations during the data‐acquisition cycle. The bulk resistivity of an acceptor‐doped morphotropic lead zirconate–titanate piezoelectric composition has been measured over the temperature range +40 to +200 °C. The activation energy derived from the experimental data is compared to the published values of similar morphotropic compositions.